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Module 25
Switch Stacking and Chassis Aggregation
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# 📘 CCNA 200-301 - Video 25: Switch Stacking and Chassis Aggregation ## Deep Study Notes --- ## 📌 Learning Objectives By the end of this video, you should understand: - Switch stacking concepts and benefits - StackWise technology - Stack members and roles (Active, Standby, Member) - Stack management and troubleshooting - Chassis aggregation (VSS, vPC) - Comparison of stacking technologies --- ## 🧠 Core Concepts ### 1. What is Switch Stacking? **Definition:** Switch stacking is a technology that connects multiple physical switches together to operate as a single logical switch, sharing a single management IP, configuration, and forwarding plane. **Analogy:** Think of switch stacking like a team of workers who share the same brain. Each worker (switch) has their own arms (ports), but they all think as one unit, share the same instructions (configuration), and can pass work between them seamlessly. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ INDIVIDUAL SWITCHES vs. STACK │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ INDIVIDUAL SWITCHES (Standalone): │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ Switch A Switch B Switch C │ │ │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ │ │ Mgmt IP │ │ Mgmt IP │ │ Mgmt IP │ │ │ │ │ │ Config │ │ Config │ │ Config │ │ │ │ │ │ 24 Ports│ │ 24 Ports│ │ 24 Ports│ │ │ │ │ └─────────┘ └─────────┘ └─────────┘ │ │ │ │ │ │ │ │ │ │ │ └─────────────────┼─────────────────┘ │ │ │ │ │ │ │ │ │ Separate Management │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ SWITCH STACK (Logical Switch): │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ ┌─────────────────────────────────────────────────────────────┐ │ │ │ │ │ Logical Switch (Stack) │ │ │ │ │ │ Single Mgmt IP, Single Config │ │ │ │ │ │ 72 Ports Total │ │ │ │ │ └─────────────────────────────────────────────────────────────┘ │ │ │ │ │ │ │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ │ │ Switch │ │ Switch │ │ Switch │ │ │ │ │ │ A │══│ B │══│ C │ │ │ │ │ │(Member) │ │(Active) │ │(Member) │ │ │ │ │ └─────────┘ └─────────┘ └─────────┘ │ │ │ │ │ │ │ │ │ │ │ └────────────┼────────────┘ │ │ │ │ │ │ │ │ │ StackWise Cables │ │ │ │ (Ring Topology) │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 2. Stacking Benefits | Benefit | Description | |---------|-------------| | **Simplified Management** | Single IP address, single configuration file | | **High Availability** | Stateful failover, redundancy | | **Scalability** | Add ports by adding switches | | **Increased Bandwidth** | Stack bandwidth between switches (up to 480 Gbps) | | **Cross-Stack EtherChannel** | EtherChannel across multiple switches in stack | | **Single Spanning Tree** | One STP instance for the entire stack | ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ STACKING BENEFITS - CROSS-STACK ETHERCHANNEL │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Without Stacking: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ Switch A ──────────────────┐ │ │ │ │ (EtherChannel) │ │ │ │ │ Switch B ──────────────────┼─── Server │ │ │ │ │ │ │ │ │ (Can't create EtherChannel across separate switches) │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ With Stacking: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ Stack (Logical Switch) │ │ │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ │ │ Switch │ │ Switch │ │ Switch │ │ │ │ │ │ A │ │ B │ │ C │ │ │ │ │ └────┬────┘ └────┬────┘ └────┬────┘ │ │ │ │ │ │ │ │ │ │ │ └────────────┼────────────┘ │ │ │ │ │ │ │ │ │ Cross-Stack EtherChannel │ │ │ │ │ │ │ │ │ ▼ │ │ │ │ ┌─────────┐ │ │ │ │ │ Server │ │ │ │ │ └─────────┘ │ │ │ │ │ │ │ │ (EtherChannel can span across multiple switches in stack) │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 3. StackWise Technology **StackWise (Cisco):** High-speed stacking technology using special stacking cables. | Technology | Speed | Max Switches | Platforms | |------------|-------|--------------|-----------| | **StackWise** | 32 Gbps | 9 | 3750, 2960-S, 2960-X | | **StackWise-80** | 80 Gbps | 9 | 3750-X, 3850 | | **StackWise-160** | 160 Gbps | 9 | 3650, 3850, 9300 | | **StackWise-480** | 480 Gbps | 9 | 9300, 9400, 9500 | | **StackWise Virtual** | Varies | 2 | 9000 series, 6800 series | ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ STACKWISE RING TOPOLOGY │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Physical Ring Topology: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ ┌─────────────────┐ │ │ │ │ ┌────────│ Switch 1 │────────┐ │ │ │ │ │ │ (Active) │ │ │ │ │ │ │ └─────────────────┘ │ │ │ │ │ │ │ │ │ │ │ StackWise Cable StackWise Cable │ │ │ │ │ │ │ │ │ │ │ ┌─────────────────┐ │ │ │ │ │ └────────│ Switch 2 │────────┘ │ │ │ │ │ (Standby) │ │ │ │ │ └─────────────────┘ │ │ │ │ │ │ │ │ │ StackWise Cable │ │ │ │ │ │ │ │ │ ┌─────────────────┐ │ │ │ │ │ Switch 3 │ │ │ │ │ │ (Member) │ │ │ │ │ └─────────────────┘ │ │ │ │ │ │ │ │ Ring Topology Benefits: │ │ │ │ • Redundancy (if one cable fails, ring stays up) │ │ │ │ • Full bandwidth between all switches │ │ │ │ • Auto-discovery of new switches │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 4. Stack Roles | Role | Description | Responsibilities | |------|-------------|------------------| | **Active (Master)** | Primary switch in stack | Manages entire stack, runs routing protocols, holds configuration | | **Standby** | Backup to Active | Takes over if Active fails, synchronizes configuration | | **Member** | Non-master switches | Forward traffic, follow Active's configuration | ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ STACK ROLES AND FAILOVER │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ NORMAL OPERATION: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ │ │ Active │ │ Standby │ │ Member │ │ │ │ │ │ Switch1 │◄──────►│ Switch2 │◄──────►│ Switch3 │ │ │ │ │ │ Priority│ │ Priority│ │ Priority│ │ │ │ │ │ 15 │ │ 14 │ │ 13 │ │ │ │ │ └─────────┘ └─────────┘ └─────────┘ │ │ │ │ │ │ │ │ │ │ │ └──────────────────┼──────────────────┘ │ │ │ │ │ │ │ │ │ Single Management IP │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ │ ACTIVE FAILS: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ │ │ │ │ ┌─────────┐ ┌─────────┐ ┌─────────┐ │ │ │ │ │ X X │ │ Active │ │ Member │ │ │ │ │ │ Switch1 │ │ Switch2 │◄──────►│ Switch3 │ │ │ │ │ │ (Failed)│ │(Takes │ │ │ │ │ │ │ └─────────┘ │ Over) │ └─────────┘ │ │ │ │ └─────────┘ │ │ │ │ │ │ │ │ • Standby becomes Active │ │ │ │ • New Standby elected from remaining members │ │ │ │ • Traffic continues (sub-second failover) │ │ │ │ │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 5. Stack Election Process **Election Criteria (in order):** 1. **Current Active** (if present and stable) 2. **Highest Priority** (1-15, default 1) 3. **Lowest MAC Address** (if priorities equal) ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ STACK ELECTION PROCESS │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Step 1: Switches power on │ │ │ │ │ ▼ │ │ Step 2: Switches discover neighbors via stack cables │ │ │ │ │ ▼ │ │ Step 3: Election based on priority (higher is better) │ │ │ │ │ ├─── Switch A (Priority 15) ───► Becomes Active │ │ ├─── Switch B (Priority 14) ───► Becomes Standby │ │ └─── Switch C (Priority 13) ───► Becomes Member │ │ │ │ Setting Priority: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ Switch(config)# switch 1 priority 15 │ │ │ │ Switch(config)# switch 2 priority 14 │ │ │ │ Switch(config)# switch 3 priority 13 │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 6. Stack Configuration **Basic Stack Configuration:** ```cisco ! View stack members Switch# show switch ! Set stack member priority Switch(config)# switch 1 priority 15 Switch(config)# switch 2 priority 14 Switch(config)# switch 3 priority 13 ! Set stack member number (permanent) Switch(config)# switch 1 renumber 1 Switch(config)# switch 2 renumber 2 Switch(config)# switch 3 renumber 3 ! Set stack member name Switch(config)# switch 1 provision ws-c3850-24p Switch(config)# switch 2 provision ws-c3850-24p Switch(config)# switch 3 provision ws-c3850-24p ! Verify stack configuration Switch# show switch Switch# show switch neighbors Switch# show switch stack-ports ``` **Stack Configuration Example Output:** ```cisco Switch# show switch Switch/Stack Mac Address : 001a.2b3c.4d5e H/W Current Switch# Role Mac Address Priority Version State ----------------------------------------------------------- *1 Active 001a.2b3c.4d5e 15 V01 Ready 2 Standby 001a.2b3c.4d5f 14 V01 Ready 3 Member 001a.2b3c.4d60 13 V01 Ready Switch# show switch neighbors Switch # Port 1 Port 2 ---------- --------- --------- 1 2 3 2 1 3 3 2 1 ``` --- ### 7. Stack Provisioning **Provisioning:** Pre-configuring a stack member before it physically joins the stack. ```cisco ! Pre-provision a switch (before it's physically added) Switch(config)# switch 4 provision ws-c3850-48p Switch(config)# interface gigabitEthernet 4/0/1 Switch(config-if)# description Pre-provisioned port Switch(config-if)# switchport mode access Switch(config-if)# switchport access vlan 10 ! After switch is added, configuration is automatically applied ``` **Benefits of Provisioning:** - Port configurations ready when switch joins - Consistent configuration across stack - Plug-and-play addition of switches --- ### 8. Stack Upgrade and Maintenance **In-Service Software Upgrade (ISSU):** ```cisco ! Perform ISSU (zero downtime upgrade) Switch# software install file flash:cat3k_caa-universalk9.SPA.03.06.06.E.152-2.E6.bin ! Install on standby and members first, then active Switch# software upgrade ``` **Rolling Stack Upgrade:** ```cisco ! Upgrade stack with minimal downtime Switch# software install file flash:new-image.bin new-reload ! Switches upgrade one at a time ! Traffic continues through other switches ``` --- ### 9. Chassis Aggregation - VSS (Virtual Switching System) **Definition:** VSS is a Cisco technology that combines two physical chassis into a single logical switch, similar to stacking but for chassis-based switches. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ VSS (Virtual Switching System) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Physical View (Two Chassis): │ │ ┌─────────────────┐ ┌─────────────────┐ │ │ │ Chassis 1 │ │ Chassis 2 │ │ │ │ (Switch A) │ │ (Switch B) │ │ │ │ │ │ │ │ │ │ Supervisor │ │ Supervisor │ │ │ │ Module │ │ Module │ │ │ │ │ │ │ │ │ │ Line Cards │ │ Line Cards │ │ │ └────────┬────────┘ └────────┬────────┘ │ │ │ │ │ │ └──────────────┬───────────────────────┘ │ │ │ │ │ Virtual Switch Link (VSL) │ │ 10/40/100 Gbps │ │ │ │ Logical View (One Switch): │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ Virtual Switch (VSS) │ │ │ │ Single Management IP │ │ │ │ Single Configuration │ │ │ │ Up to 576 Ports │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` **VSS Features:** - Up to 2 chassis (Catalyst 4500, 6500, 6800, 9500) - Virtual Switch Link (VSL) between chassis - Stateful failover (sub-second) - Multi-chassis EtherChannel (MEC) - Single management plane --- ### 10. vPC (Virtual Port Channel) **Definition:** vPC is a Cisco technology (NX-OS) that allows EtherChannel to span across two separate physical switches without requiring a stack or VSS. ``` ┌─────────────────────────────────────────────────────────────────────────────┐ │ vPC (Virtual Port Channel) │ ├─────────────────────────────────────────────────────────────────────────────┤ │ │ │ Physical View: │ │ ┌─────────────────┐ ┌─────────────────┐ │ │ │ Switch A │ │ Switch B │ │ │ │ (vPC Peer) │ │ (vPC Peer) │ │ │ │ │ │ │ │ │ │ Port1 ────────┼────────────────────┼─────── Port1 │ │ │ │ │ │ │ │ │ │ Port2 ────────┼────────────────────┼─────── Port2 │ │ │ └─────────────────┘ └─────────────────┘ │ │ │ │ │ │ │ vPC Peer Link │ │ │ └─────────────────────────────────────┘ │ │ │ │ │ │ │ │ ┌──────▼──────┐ │ │ │ Server │ │ │ │ (vPC Client)│ │ │ │ PortChannel │ │ │ └─────────────┘ │ │ │ │ Logical View: Server sees single PortChannel │ │ │ │ vPC vs. VSS: │ │ ┌─────────────────────────────────────────────────────────────────────┐ │ │ │ vPC: │ │ │ │ • Separate control planes │ │ │ │ • NX-OS platforms (Nexus) │ │ │ │ • Up to 2 switches (more with vPC+) │ │ │ │ │ │ │ │ VSS: │ │ │ │ • Unified control plane │ │ │ │ • IOS/IOS-XE platforms (Catalyst) │ │ │ │ • Only 2 switches │ │ │ └─────────────────────────────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────────────────────────────┘ ``` --- ### 11. Stacking Comparison | Feature | StackWise | VSS | vPC | |---------|-----------|-----|-----| | **Platform** | Catalyst 2K/3K/9K | Catalyst 4K/6K/9K | Nexus 3K/5K/7K/9K | | **Max Switches** | 9 | 2 | 2 (more with vPC+) | | **Control Plane** | Unified | Unified | Separate | | **Management** | Single IP | Single IP | Separate IPs | | **EtherChannel** | Cross-Stack | Multi-Chassis | Virtual Port Channel | | **Failover Time** | Sub-second | Sub-second | Sub-second | | **Distance** | Short (cables) | Up to 100km | Up to 100km | | **Cost** | Low | High | Medium | --- ### 12. Stack Troubleshooting | Problem | Symptom | Solution | |---------|---------|----------| | **Stack Not Forming** | Switches show as separate | Check stack cables, power cycle | | **Active Election Issue** | Wrong switch is Active | Verify priorities, set desired Active | | **Inconsistent Software** | Version mismatch | Upgrade all switches to same version | | **Stack Split** | Stack splits into two | Check cables, ensure ring topology | | **Port Not Working** | Member switch ports down | Verify switch is Ready state | **Troubleshooting Commands:** ```cisco ! Check stack status Switch# show switch ! Check stack cables Switch# show switch stack-ports ! Check stack ring status Switch# show switch stack-ring ! Check stack bandwidth Switch# show switch stack-bandwidth ! Check stack members details Switch# show switch detail ! Check stack neighbors Switch# show switch neighbors ``` --- ## 🔧 Complete Configuration Examples ### Lab 1: Stack Configuration (3 Switches) **Topology:** ``` Switch 1 (Priority 15 - Active) │ StackWise Cable │ Switch 2 (Priority 14 - Standby) │ StackWise Cable │ Switch 3 (Priority 13 - Member) ``` **Initial Setup (After Stack is Formed):** ```cisco ! On any switch in stack (configuration applies to entire stack) Switch# configure terminal ! Set stack member priorities Switch(config)# switch 1 priority 15 Switch(config)# switch 2 priority 14 Switch(config)# switch 3 priority 13 ! Set stack member numbers (permanent) Switch(config)# switch 1 renumber 1 Switch(config)# switch 2 renumber 2 Switch(config)# switch 3 renumber 3 ! Configure stack-wide settings Switch(config)# spanning-tree mode rapid-pvst Switch(config)# vlan 10 Switch(config-vlan)# name Engineering Switch(config-vlan)# exit Switch(config)# vlan 20 Switch(config-vlan)# name Sales Switch(config-vlan)# exit ! Configure cross-stack EtherChannel to server Switch(config)# interface port-channel 1 Switch(config-if)# switchport mode trunk Switch(config-if)# exit ! Add ports from different switches to EtherChannel Switch(config)# interface range gigabitEthernet 1/0/1, gigabitEthernet 2/0/1, gigabitEthernet 3/0/1 Switch(config-if-range)# channel-group 1 mode active Switch(config-if-range)# exit ! Verify Switch# show etherchannel summary Switch# show switch ``` --- ### Lab 2: Stack Provisioning (Adding Fourth Switch) **Step 1: Pre-provision New Switch** ```cisco ! Pre-provision switch 4 before physical connection Switch(config)# switch 4 provision ws-c3850-48p Switch(config)# interface range gigabitEthernet 4/0/1-24 Switch(config-if-range)# switchport mode access Switch(config-if-range)# switchport access vlan 10 Switch(config-if-range)# spanning-tree portfast Switch(config-if-range)# exit ! Verify provisioning Switch# show switch 4 ! Output shows "Provisioned" state ``` **Step 2: Physically Connect Switch 4** ``` ! Connect StackWise cables: ! Switch 3 Stack Port 2 → Switch 4 Stack Port 1 ! Switch 4 Stack Port 2 → Switch 1 Stack Port 1 ``` **Step 3: Verify New Switch** ```cisco ! New switch auto-joins stack Switch# show switch ! Switch 4 should show "Ready" state ! Configuration automatically applied ``` --- ### Lab 3: Stack Upgrade **Step 1: Verify Current Version** ```cisco Switch# show version | include Version ! Output: Cisco IOS Software, Version 03.06.06.E ``` **Step 2: Copy New Image** ```cisco Switch# copy tftp flash: Address or name of remote host []? 192.168.1.100 Source filename []? cat3k_caa-universalk9.SPA.03.07.05.E.152-3.E5.bin Destination filename []? cat3k_caa-universalk9.SPA.03.07.05.E.152-3.E5.bin ``` **Step 3: Perform Rolling Upgrade** ```cisco ! Rolling upgrade (upgrades one switch at a time) Switch# software install file flash:cat3k_caa-universalk9.SPA.03.07.05.E.152-3.E5.bin new-reload ! Verify upgrade Switch# show version | include Version ! All switches now on new version ``` --- ## ✅ Exam Tips (For CCNA 200-301) | Topic | What Cisco Tests | |-------|------------------| | **Stack Roles** | Active, Standby, Member | | **Election Criteria** | Priority (higher wins), then MAC address | | **StackWise** | Ring topology, 32-480 Gbps, up to 9 switches | | **Cross-Stack EtherChannel** | EtherChannel across multiple stack members | | **Provisioning** | Pre-configuring switches before addition | | **VSS** | 2 chassis, unified control plane | | **vPC** | 2 switches, separate control planes | ### Common Exam Scenarios: **Scenario 1:** "A stack has 3 switches with priorities 1, 1, and 1. Which becomes Active?" - **Answer:** The switch with the lowest MAC address **Scenario 2:** "A switch in a stack fails. How does traffic continue?" - **Answer:** Standby becomes Active; member switches continue forwarding **Scenario 3:** "A server needs 4 Gbps of bandwidth but only has 1 Gbps NICs. How can stacking help?" - **Answer:** Cross-stack EtherChannel across multiple stack members provides 4 Gbps (4x1Gbps) to the server ### Mnemonics: **Stack Election:** **"P-M" - Priority then MAC** - **P**riority (higher wins) - **M**AC (lower wins if priorities equal) **Stack Roles:** **"A-S-M" - Active, Standby, Member** - **A**ctive: Master, runs config - **S**tandby: Backup to Active - **M**ember: Follows Active --- ## 📝 Summary (1-Minute Revision) ``` SWITCH STACKING: DEFINITION: ├── Multiple switches operate as single logical switch ├── Single management IP, single config ├── Up to 9 switches (StackWise) STACK ROLES: ├── Active: Master, runs configuration ├── Standby: Backup to Active └── Member: Follows Active ELECTION: ├── Current Active (if stable) ├── Highest priority (1-15, default 1) └── Lowest MAC address (if priorities equal) STACKWISE: ├── Ring topology (redundant) ├── 32-480 Gbps stack bandwidth ├── Up to 9 switches └── Auto-discovery BENEFITS: ├── Simplified management ├── High availability (sub-second failover) ├── Cross-stack EtherChannel ├── Scalability └── Single STP instance PROVISIONING: ├── Pre-configure before physical addition ├── Port configs ready when switch joins └── Plug-and-play CHASSIS AGGREGATION: ├── VSS: 2 chassis, unified control plane ├── vPC: 2 switches, separate control planes └── Multi-chassis EtherChannel (MEC) VERIFICATION: ├── show switch ├── show switch neighbors ├── show switch stack-ports └── show switch stack-ring ``` --- ## 🧪 Practice Questions **1. What is the maximum number of switches in a Cisco StackWise stack?** - A) 4 - B) 6 - C) 9 - D) 12 <details> <summary>Answer</summary> <b>C) 9</b> - StackWise supports up to 9 switches in a stack. </details> **2. Which switch becomes Active in a stack?** - A) Switch with highest priority - B) Switch with lowest priority - C) Switch with highest MAC address - D) Switch with lowest MAC address <details> <summary>Answer</summary> <b>A) Switch with highest priority</b> - Higher priority wins; if equal, lowest MAC wins. </details> **3. What is the default stack priority on Cisco switches?** - A) 0 - B) 1 - C) 10 - D) 15 <details> <summary>Answer</summary> <b>B) 1</b> - Default priority is 1 (range 1-15). </details> **4. Which topology does StackWise use?** - A) Star - B) Bus - C) Ring - D) Mesh <details> <summary>Answer</summary> <b>C) Ring</b> - StackWise uses a ring topology for redundancy. </details> **5. What is the benefit of cross-stack EtherChannel?** - A) Faster STP convergence - B) EtherChannel across multiple switches in stack - C) Better security - D) Easier management <details> <summary>Answer</summary> <b>B) EtherChannel across multiple switches in stack</b> - Allows load balancing and redundancy across stack members. </details> **6. Which command displays stack members?** - A) `show stack` - B) `show switch` - C) `show members` - D) `show stack members` <details> <summary>Answer</summary> <b>B) `show switch`</b> - Displays all stack members with roles and status. </details> **7. What happens when the Active switch fails?** - A) Entire stack stops forwarding - B) Standby becomes Active - C) Stack reboots - D) Traffic stops for 50 seconds <details> <summary>Answer</summary> <b>B) Standby becomes Active</b> - Standby takes over with sub-second failover. </details> **8. Which technology combines two chassis into a single logical switch?** - A) StackWise - B) VSS (Virtual Switching System) - C) vPC - D) EtherChannel <details> <summary>Answer</summary> <b>B) VSS (Virtual Switching System)</b> - VSS combines two Catalyst chassis into one logical switch. </details> **9. What is the purpose of stack provisioning?** - A) Configure ports before switch is added - B) Remove switches from stack - C) Change stack priority - D) Upgrade stack software <details> <summary>Answer</summary> <b>A) Configure ports before switch is added</b> - Pre-provisioning allows configuration before physical addition. </details> **10. Which command sets stack member priority?** - A) `priority 15` - B) `switch 1 priority 15` - C) `stack priority 15` - D) `member priority 15` <details> <summary>Answer</summary> <b>B) `switch 1 priority 15`</b> - This sets the priority for stack member 1. </details> **11. What is the role of the Standby switch in a stack?** - A) Forwards no traffic - B) Backup to Active, ready to take over - C) Only manages management traffic - D) Only handles broadcast traffic <details> <summary>Answer</summary> <b>B) Backup to Active, ready to take over</b> - Standby synchronizes with Active and takes over if Active fails. </details> **12. Which technology allows EtherChannel across two separate switches without stacking?** - A) StackWise - B) VSS - C) vPC - D) Both B and C <details> <summary>Answer</summary> <b>D) Both B and C</b> - Both VSS and vPC allow multi-chassis EtherChannel. </details> --- ## 📌 Next Steps After completing Video 25, you should be ready for: - **Video 26:** Route Summarization - **Video 27:** OSPF Network Types **Lab Practice:** 1. Build a stack with 3 switches (if hardware available) 2. Verify stack formation with `show switch` 3. Set priorities to control Active election 4. Configure cross-stack EtherChannel to a server 5. Pre-provision a fourth switch 6. Perform rolling software upgrade --- **Ready for Video 26?** Share the link or say "next" and I'll continue with Route Summarization. I'll continue with **Video 26: Route Summarization** based on the standard CCNA 200-301 curriculum. ---